Exact exchange with non-orthogonal generalized Wannier functions

Area of Science:

• Quantum Chemistry
• Computational Materials Science
• Solid-State Physics

Background:

• Evaluating exact exchange (EXX) is crucial for accurate ab initio and hybrid density functional calculations.
• The non-local nature of the exchange operator hinders efficient EXX calculations with planewave basis sets.
• Non-orthogonal generalized Wannier functions (NGWFs) offer a suitable alternative basis set for periodic systems.

Purpose of the Study:

• To investigate the use of NGWFs for evaluating exact exchange in periodic systems.
• To present an approach for constructing the exchange operator using NGWFs.
• To assess the computational efficiency of the NGWF approach for EXX calculations.

Main Methods:

• Utilized NGWFs derived from Fourier series representations of atom-centered basis sets.
• Developed a method to construct the exchange operator with NGWFs.
• Performed Hartree-Fock calculations on molecules in periodically repeated cells.

Main Results:

• Demonstrated the feasibility of using NGWFs for EXX evaluation in periodic systems.
• The NGWF approach significantly reduces computational cost compared to standard methods.
• Achieved substantial speed-up in calculations for periodic systems.

Conclusions:

• NGWFs provide an efficient alternative for incorporating exact exchange in periodic quantum chemical calculations.
• This method overcomes the limitations of planewave basis sets for EXX.
• The NGWF approach offers a promising direction for accelerating large-scale electronic structure calculations.